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Prenatal WIC participation in relation to low birth weight and Medicaid infant costs in North Carolina : a 1997 update

CHIS Study No. 122 4 Center for Health Informatics and Statistics
rates of low and very low birth weight than women
who did not participate in WIC. The women who
participated in WIC were more likely than those
who did not participate to be unmarried, of low
education, and under age 18. Also, the WIC group
was substantially more likely to have a quantita-tively
adequate level of prenatal care and to have
received Medicaid case management services dur-ing
pregnancy. The logistic regression analyses in
Table 2 confirm the findings from Table 1 of lower
rates of low and very low birth weight among the
WIC births. Women who did not participate in WIC
have an odds of low birth weight 1.36 times that of
the women who did participate in WIC, controlling
for other risk factors for low birth weight. The ad-justed
odds ratio for very low birth weight for the
WIC non- participants was 1.90. An ordinary least
squares regression with grams of birth weight as a
continuous dependent variable also showed a
statistically significant positive effect for WIC.
After controlling for the risk factors shown in Table
2, WIC non- participation was associated with an
average 61 grams lower birth weight ( p=. 0001).
Table 3 suggests that $ 1.99 was saved in newborn
Medicaid costs ( for services beginning within 60
days of birth) for every dollar spent by WIC in the
prenatal period. These cost savings figures are
$ 1.44 for white births and $ 4.02 for minority births.
Using regression analysis to determine an adjusted
cost difference between WIC and non- WIC births
produces higher cost savings estimates for white
and total Medicaid births ( Table 3, last column).
This change is consistent with the finding that the
WIC group is at higher risk for low birth weight on
several of the demographic characteristics; adjust-ing
for these characteristics in effect reduces the
cost estimates for the WIC group.
Table 2.
Adjusted odds ratios ( ORs) from logistic regression and 95% confidence intervals ( CIs)
for selected maternal risk factors for low birth weight among 42,965 live births to North
Carolina women receiving Medicaid benefits in 1997a
Low Very low
birth weight birth weight
(< 2500 g) (< 1500 g)
Risk factors OR CI OR CI
One or more medical risk 2.66 2.49, 2.85 4.71 4.02, 5.53
factors on birth certificateb
Minority status 1.63 1.51, 1.76 1.85 1.57, 2.19
Smoked cigarettes 1.68 1.55, 1.80 1.29 1.09, 1.54
Not enrolled in WICc 1.36 1.26, 1.48 1.90 1.61, 2.25
Previous fetal death or live 1.22 1.13, 1.31 1.50 1.28, 1.75
born who died
Age < 18 years 1.12 1.00, 1.25 1.36 1.05, 1.76
No Medicaid case 0.98 0.91, 1.06 1.14 0.97, 1.34
management
Less than adequate 1.21 1.13, 1.30 1.04 0.89, 1.22
prenatal cared
Education < 12 years 1.15 1.07, 1.24 0.91 0.77, 1.08
Unmarried 1.13 1.04, 1.22 1.22 1.03, 1.45
aBirths to mothers who received no prenatal care and multiple births are excluded. Records with missing values for any
variable are excluded.
bThese risk factors include anemia, cardiac disease, diabetes, hypertension, eclampsia, renal disease, and previous
preterm infant ( same as in 1988 study).
cMother was not enrolled in WIC at all during pregnancy.
dAdequacy of prenatal care determined using the Kessner index.

CHIS Study No. 122 4 Center for Health Informatics and Statistics
rates of low and very low birth weight than women
who did not participate in WIC. The women who
participated in WIC were more likely than those
who did not participate to be unmarried, of low
education, and under age 18. Also, the WIC group
was substantially more likely to have a quantita-tively
adequate level of prenatal care and to have
received Medicaid case management services dur-ing
pregnancy. The logistic regression analyses in
Table 2 confirm the findings from Table 1 of lower
rates of low and very low birth weight among the
WIC births. Women who did not participate in WIC
have an odds of low birth weight 1.36 times that of
the women who did participate in WIC, controlling
for other risk factors for low birth weight. The ad-justed
odds ratio for very low birth weight for the
WIC non- participants was 1.90. An ordinary least
squares regression with grams of birth weight as a
continuous dependent variable also showed a
statistically significant positive effect for WIC.
After controlling for the risk factors shown in Table
2, WIC non- participation was associated with an
average 61 grams lower birth weight ( p=. 0001).
Table 3 suggests that $ 1.99 was saved in newborn
Medicaid costs ( for services beginning within 60
days of birth) for every dollar spent by WIC in the
prenatal period. These cost savings figures are
$ 1.44 for white births and $ 4.02 for minority births.
Using regression analysis to determine an adjusted
cost difference between WIC and non- WIC births
produces higher cost savings estimates for white
and total Medicaid births ( Table 3, last column).
This change is consistent with the finding that the
WIC group is at higher risk for low birth weight on
several of the demographic characteristics; adjust-ing
for these characteristics in effect reduces the
cost estimates for the WIC group.
Table 2.
Adjusted odds ratios ( ORs) from logistic regression and 95% confidence intervals ( CIs)
for selected maternal risk factors for low birth weight among 42,965 live births to North
Carolina women receiving Medicaid benefits in 1997a
Low Very low
birth weight birth weight
(< 2500 g) (< 1500 g)
Risk factors OR CI OR CI
One or more medical risk 2.66 2.49, 2.85 4.71 4.02, 5.53
factors on birth certificateb
Minority status 1.63 1.51, 1.76 1.85 1.57, 2.19
Smoked cigarettes 1.68 1.55, 1.80 1.29 1.09, 1.54
Not enrolled in WICc 1.36 1.26, 1.48 1.90 1.61, 2.25
Previous fetal death or live 1.22 1.13, 1.31 1.50 1.28, 1.75
born who died
Age < 18 years 1.12 1.00, 1.25 1.36 1.05, 1.76
No Medicaid case 0.98 0.91, 1.06 1.14 0.97, 1.34
management
Less than adequate 1.21 1.13, 1.30 1.04 0.89, 1.22
prenatal cared
Education < 12 years 1.15 1.07, 1.24 0.91 0.77, 1.08
Unmarried 1.13 1.04, 1.22 1.22 1.03, 1.45
aBirths to mothers who received no prenatal care and multiple births are excluded. Records with missing values for any
variable are excluded.
bThese risk factors include anemia, cardiac disease, diabetes, hypertension, eclampsia, renal disease, and previous
preterm infant ( same as in 1988 study).
cMother was not enrolled in WIC at all during pregnancy.
dAdequacy of prenatal care determined using the Kessner index.